植物地境及物种地境稳定层

Plant Below-Ground Habitat and Stable Layer of Plant Species in Habitat

植物地境是其生境的重要组成部分 .地境结构的系统分析应作为探索植物与其地境生态关系的重要手段之一 .植物地境具有鲜明的耗散结构特征 ,内部的宏观稳定性和层次性是适应外界环境的自组织结果 ,并与植物根群的“层片”结构相契合 .每一“层片”代表一个特定的地下小环境 .若地境具有多个“层片” ,说明该地境拥有可被多种植物利用的多样小环境 .根群作为根系的主功能区 ,是联系植物与地境的纽带 .与植物的根系相比 ,根群的“层片”现象更清晰 .通过根群的“层片” ,不同植物实现资源分割 ,避免过激竞争 ,能够长期共存 .基于地境耗散结构特征分析和各物种根群所处深度范围的统计结果 ,首次建立了物种地境稳定层的概念 .某一物种根群所处的位置即为该物种的地境稳定层 .物种地境稳定层可作为地境生态功能分层的基本单位 .较之地境全剖面各指标的平均值 ,地境稳定层内理化指标组态更为真实地反映了植物生存的地下环境 ,可用以确定物种的生存域 ;不同植物的生理和生活习性是对其稳定层内指标组态量值及动态变化规律的一种响应 ;地境所能提供的稳定层的多寡及组态对地表植物群落的结构具有一定的控制作用 ;地境稳定层的消失和产生 ,可导致对应物种的消亡和入侵 ,造成植物群落的演替 .

Plant below-ground habitat is an important part of the plant habitat, and the systemic analysis of its structure should be emphasized in seeking for the regulations of the ecological relationship between plant and its habitat. Remarkable characteristics of the dissipative structure are discovered in the plant below-ground habitat, made up of many layers displaying macroscopic stability as a result of the self-organization. This layered structure of the plant below-ground habitat is well consistent with the synusium of the root masses. This synusium allows us to predict that each layer means one special below-ground little living environment for the root mass of the plant species, and if the below-ground habitat is made up of many such layers, it would provide various little below-ground living environments for different plant species. In the analysis, the root mass of the plant, defined as the part of the roots performing the major function of absorbing soil resources, is the linchpin between the plant and its below-ground habitat. Compared with the root system, the synusium of the root masses (among) different plants is clearer, by which, different plants can partition the resources in different deep layers to avoid intensive competition and coexist for long term. Based on the analysis of the dissipative structure of plant below-ground habitat and statistical results about the depth of the species root mass, the concept ”stable layer of plant species in below-ground habitat” (SLPSBH) is built, which can be determined by the position of the root mass and used as the basic unit for layering the plant below-ground habitat in view of its ecological function. With the concept, we may predict that (1) the configuration of physical and chemical indexes in the stable layer can characterize the below-ground living environment of the plant more truly than the averages of the indexes in whole soil profile, (2) some life habits and physiological characteristics of the plant species is built on long-term adapt to the value and dynamic of the configuration in its stable layer, (3) it may be how many SLPSBH can be provided in below-ground habitat for different plant species that determines the structural features of the plant community, and (4) the plant species which SLPSBH exists no longer would disappear from the community, while the new comers may invade for they can find their SLPSBH, leading to the succession of the plant community.